ProbioticsPrebioticsWhataretheyallabout

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1、Probiotics&Prebiotics-What are they all about?marketing gimmick or tool?Background Probiotics are dietary supplements containing potentially beneficial bacteria or yeast,with lactic acid bacteria(LAB).LAB have been used in the food industry for many years,because they are able to convert sugars and

2、other carbohydrates into lactic acid.This provides the characteristic sour taste of fermented dairy foods such as yogurt,and acts as a preservative,by lowering the pHAnd Prebiotics are a category of functional food,defined as:Non-digestible food ingredients that beneficially affect the host by selec

3、tively stimulating the growth and/or activity of one or a limited number of bacteria in the colon,and thus improve host health eg.oligosacchiridesThe Theory The body contains a miniature ecology of microbes,collectively known as the gut flora The number of bacterial types can be thrown out of balanc

4、e by a wide range of circumstances including the use of antibiotics or other drugs,excess alcohol,stress,disease,exposure to toxic substances,or even the use of antibacterial soapThe PlayersBIFIDOBACTERIUMLACTOBACILLUSLACTOCOCCUSSACCHAROMYCESSTREPTOCOCCUS THERMOPHILUSENTEROCOCCUSHow do they work?Pro

5、biotics may have antibacterial,immunomodulatory,anticarcinogenic,antidiarrhoeal,antiallergenic and antioxidant activities The antibacterial ability may partially be due to the ability to colonize the colon and reinforce the barrier function of the intestinal mucosaAlso Lactobacillus casei has been d

6、emonstrated to increase levels of circulating IgA in infants infected with rotavirus Lactobacillus acidophilus and Bifidobacterium bifidum appear to enhance the nonspecific immune phagocytic activity of circulating blood granulocytesAnd S.boulardii has been found to secrete a protease which digests

7、two protein exotoxins,toxin A and toxin B,which appear to mediate diarrhoea and colitis caused by Clostridium difficile Lactobacillus rhamnosus GG and Bifidobacterium lactis Bb12 produce significant improvement of atopic eczema in children:the decrease in the signs and symptoms occurred in parallel

8、with a reduction in the concentration of circulating CD4+T lymphocytes and an increase in TGF-beta1,indicating suppressive effects on T cell functions in this disorderReally?Do they survive in the acidic stomach environment,the alkaline conditions in the duodenum,as well as their ability to adhere t

9、o the intestinal mucosa of the colon and to colonize the colon.Some probiotics,such as Lactobacillus GG and Lactobacillus plantarum 299v,do.After passage through the stomach and the small intestine,they become established transiently in the colon.The Fanclub Dr.Elie Metchnikoff,the father of modern

10、immunology Dr.Minoru Shirota,Yakult Dr Jean-Michel Antoine,science director at DanoneAll bar the first may have conflicts of interest but it does get betterEvidence of effects Vandenplas et al in Eur J Paeds 2007 indicated selected strains of probiotics result in a statistically significant but clin

11、ically moderate benefit in shortening the duration of diarrhoea caused by acute infectious gastroenteritis Tellado in Cur Opin Crit Care 2007 indicate that they may contribute to better prognosis in pancreatitisFurthur papers Nomura et al in Hepatogastroenterology 2007 showed probiotics reduce the r

12、ate of infection after Whipples procedure Moayeddi in EBM 2007 indicated that used of probiotics in H pylori eradication therapy improved efficacy and reduced s/eNow for us GPs Hickson et al BMJ 2007 indicated in a randomised double blind trial that consumption of a probiotic drink containing L case

13、i,L bulgaricus,and S thermophilus can reduce the incidence of antibiotic associated diarrhoea and C difficile associated diarrhoea Cochrane indicate they may be of use in AAD and infective diarrhoea in conjunction with ORTSo I suggest when giving antibiotics to all age groups apart from pregnant and breast feeding Anecdotal evidence so far:less D&V,lower incidence of vaginal thrush,controlled diverticulosis Potential s/e theoretically include flatulence/constipation/Lactobacillus bacteraemia and endocarditis